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To prevent an attacker from setting up a DHCP server (Rogue DHCP) in the network and assign IP parameters, the function DHCP Snooping can be configured on a managed switch. In doing so "DHCP Offer" packets are only transmitted on the switch port, the DHCP server is connected to. "DHCP Offer" packets on all other ports are discarded. Furthermore, "DHCP Discover" as well as "DHCP Request" packets from a network device are only forwarded to a "Trusted" port, but not to "Untrusted" ports. This significantly lessens the amount of Broadcast packets in the network, which is especially useful in bigger scenarios.
This article describes how to configure DHCP Snooping on a GS-23xx series switch.
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